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“EXTRACTS FROM CORRESPONDENCE OF THE DIVISION. 33 
THE EFFECT OF FROST UPON SCALE-INSECTS. 
Your favor ef the 28th of December to hand on Saturday last. I have been care- 
fully examining scale insects to be able to tell you the effects of the frosts on them. 
We had frost on the 15th, 16th, 22d, 23d, 25th, 26th, and 30th of November; onthe Ist, 
2d, 3d, and 4th of December; also on the #th a frost that hurt the orange trees that had 
tender growth; again, frost on the 16th, 17th, and 18th; on the 17th we had a regular 
freeze. I measured ice five- sixteenths inch in thickness formed during the night. 
This freeze hurt many trees so that they have shed their leaves. During this cold 
weather I have kept myself informed of the condition of the insects. After each of 
the frosts in November I found migratory larve, and no signs of damage to the in- 
sects or eggs. From my note-book I read: ‘‘November 20. Young brood hatching 
out.” ‘*November 25. This morning young larvie under scales ; when disturbed they 
tun about quite lively.” ‘‘ November 30. Migratory larvee under scales unhurt.” 
** December 4. Five days’ consecutive frost; no damage to insects; numerous young 
just settled ; abundance of eggs ready to hatch.” ‘December 8. Young larvie alive 
under scales, ready to run when disturbed.” ‘‘ December 14. Four days’ consecutive 
warm weather; abundance of migratory larve.” ‘‘ December i9. Three days of con- 
secutive frost; morning of 17th (thermometer + 25° F.) found migratory larvee run- 
ning about; eggs are apparently unhurt; some moisture near ; somescales appear to be 
from the inclosed larve, but no damage to them is now visible.” ‘‘ December 27. Sev- 
eral days of wet weather followed by the frost, so that the trees were constantly wet ; 
to-day, although cloudy, the trees are dry; some larvze are dead, but a large majority 
are unhurt; no eggs showing signs of injury found; migratory larvee seen; the young 
recently settled broods did not appear to be any more hurt than the old ones.” ‘‘ De- 
_ cember 30. Wet and cold for several days past; at noon to-day clearer and warm; no 
migratory larve out; many eggs ready to hatch; some males seen issuing.” ‘* De- 
cember 31. Clear and warm ; found recently-hatched larvee and parasites ; some males 
winged and out found dead ; in some scales the mother is found dead, her eggs unhurt ; 
old females are dead, while young larve settled close by them are alive; all the eggs 
appear to be on the point of hatching.” 
These observations are principally made on trees near by my house, which are in no 
way protected from the weather; some neighbors’ trees are hurt worse and some less 
than mine. At some distant places I hear that the trees are much worse hurt by the 
frosts than they are here. If I have the opportunity I will go to some of these places 
and examine the coccids. From the notes you will see that if we do not have any 
more severe cold than we have had the insects will have a very large number to 
start the year with. The cold appears to have only killed the most exposed coccids ; 
those on the defoliated twigs suffered much more than those on twigs full-leaved, 
but in no case, on the most exposed parts of defoliated branches, have I found all 
killed. I have been careful to observe this; it recalled the survival of some on the 
exposed sides of trees in the storm in September. They evidently have difterent in- 
dividual powers of resistance to vicissitudes of the weather. 
There has not been any actual stop to reproduction during the fall and winter, and 
the cold weather has only postponed hatching and maturity. This was shown by the 
progress made in spreading from twig to twig, but the general periodical broods 
appear to have been broken up into small periods, governed by the character of the 
weather. 
There has not been the usual activity on the part of parasites, as shown by perfo- 
rated scales. 
The effect of the frost on the coccids here may be summed up as follows: Hatch- 
ing and development retarded, a small portion of larve killed, but not enough to be 
of service to the tree.—[Jos. Voyle, Gainesville, Fla., January 1, 1883. 
2594 L 3 
